What is known about the interactions between projected
human-induced changes in climate and other environmental issues (e.g.,
urban air pollution, regional acid deposition, loss of biological diversity,
stratospheric ozone depletion, and desertification and land degradation)?
What is known about environmental, social, and economic costs and benefits
and implications of these interactions for integrating climate change
response strategies in an equitable manner into broad sustainable development
strategies at the local, regional, and global scales?

Local, regional, and global environmental issues are inextricably
linked and affect sustainable development. Therefore, there are synergistic
opportunities to develop more effective response options to these environmental
issues that enhance benefits, reduce costs, and more sustainably meet
human needs.

Meeting human needs in many instances is causing
environmental degradation, which in turn threatens the ability to meet
present and future needs. For example, increased agricultural production
can be achieved through increased use of nitrogenous fertilizers, irrigation,
or the conversion of natural grasslands and forests to croplands. However,
these changes can affect the Earth's climate through the release
of greenhouse gases, lead to land degradation through erosion and salinization
of soils, and contribute to the loss of biodiversity and reduction of
carbon sequestration through the conversion and fragmentation of natural
ecological systems. Agricultural productivity can in turn be adversely
affected by changes in climate, especially in the tropics and subtropics,
loss of biodiversity and changes at the genetic and species level, and
land degradation through loss of soil fertility. Many of these changes
adversely affect food security and disproportionately impact the poor.

The primary factors underlying anthropogenic
climate change are similar to those for most environmental and socio-economic
issues -- that is, economic growth, broad technological changes, life
style patterns, demographic shifts (population size, age structure, and
migration), and governance structures. These can give rise to:

Increased demand for natural resources and
energy

Market imperfections, including subsidies that
lead to the inefficient use of resources and act as a barrier to the
market penetration of environmentally sound technologies; the lack of
recognition of the true value of natural resources; failure to appropriate
for the global values of natural resources at the local level; and failure
to internalize the costs of environmental degradation into the market
price of a resource

Limited availability and transfer of technology,
inefficient use of technologies, and inadequate investment in research
and development for the technologies of the future

Climate change affects environmental issues
such as loss of biodiversity, desertification, stratospheric ozone depletion,
freshwater availability, and air quality, and in turn climate change is
affected by many of these issues.For
example, climate change is projected to exacerbate local and regional air
pollution and delay the recovery of the stratospheric ozone layer. In addition,
climate change could also affect the productivity and composition of terrestrial
and aquatic ecological systems, with a potential loss in both genetic and
species diversity; could accelerate the rate of land degradation; and could
exacerbate problems related to freshwater quantity and quality in many areas.
Conversely, local and regional air pollution, stratospheric ozone depletion,
changes in ecological systems, and land degradation would affect the Earth's
climate by changing the sources and sinks of greenhouse gases, radiative
balance of the atmosphere, and surface albedo.

The linkages among local, regional, and global environmental
issues, and their relationship to meeting human needs, offer opportunities
to capture synergies in developing response options and reducing vulnerabilities
to climate change, although trade-offs between issues may exist.
Multiple environmental and development goals can be achieved by adopting
a broad range of technologies, policies, and measures that explicitly
recognize the inextricable linkages among environmental problems and human
needs. Addressing the need for energy, while reducing local and regional
air pollution and global climate change cost-effectively, requires an
interdisciplinary assessment of the synergies and trade-offs of meeting
energy requirements in the most economically, environmentally, and socially
sustainable manner. Greenhouse gas emissions, as well as local and regional
pollutants, could be reduced through more efficient use of energy and
increasing the share of lower carbon-emitting fossil fuels, advanced fossil-fuel
technologies (e.g., highly efficient combined cycle gas turbines, fuel
cells, and combined heat and power) and renewable energy technologies
(e.g., increased use of environmentally sound biofuels, hydropower, solar,
wind- and wave-power). Further, the increase of greenhouse gas concentrations
in the atmosphere can be reduced also by enhanced uptake of carbon through,
for example, afforestation, reforestation, slowing deforestation, and
improved forest, rangeland, wetland, and cropland management, which can
have favorable effects on biodiversity, food production, land, and water
resources. Reducing vulnerability to climate change can often reduce vulnerability
to other environmental stresses and vice versa. In some cases
there will be trade-offs. For example, in some implementations, monoculture
plantations could decrease local biodiversity.

The capacity of countries to adapt and
mitigate can be enhanced when climate policies are integrated with national
development policies including economic, social, and other environmental
dimensions. Climate mitigation and adaptation options can yield ancillary
benefits that meet human needs, improve well-being, and bring other environmental
benefits. Countries with limited economic resources and low level of technology
are often highly vulnerable to climate change and other environmental problems.

A great deal of interaction exists among
the environmental issues that multilateral environmental agreements address,
and synergies can be exploited in their implementation.
Global environmental problems are addressed in a range of individual conventions
and agreements, as well as a range of regional agreements. They may contain,
inter alia, matters of common interest and similar requirements for enacting
general objectives -- for example, implementation plans, data collection
and processing, strengthening human and infrastructural capacity, and reporting
obligations. For example, although different, the Vienna Convention for
the Protection of the Ozone Layer and the United Nations Framework Convention
on Climate Change are scientifically interrelated because many of the compounds
that cause depletion of the ozone layer are also important greenhouse gases
and because some of the substitutes for the now banned ozone-depleting substances
are greenhouse gases.